The invention relates generally to semiconductor processing, and in one embodiment, to a method for making small gaps for micro electromechanical systems (MEMS) devices, or small electrical/mechanical devices.
Many different integrated circuit devices sometimes require one or more small gaps placed within the circuit. For example, MEMS devices and other small electrical/mechanical devices may incorporate a gap in the device to allow the device to respond to mechanical stimuli. One common MEMS device is a sensor, such as an accelerometer, for detecting external force, acceleration or the like by electrostatically or magnetically floating a portion of the device. The floating portion can then move responsive to the acceleration and the device can detect the movement accordingly. In some cases, the device has a micro spherical body referred to as a core, and a surrounding portion referred to as a shell. Electrodes in the shell serve not only to levitate the core by generating an electric or magnetic field, but to detect movement of the core within the shell by measuring changes in capacitance and/or direct contact of the core to the shell.
Conventionally, the core and the shell are separately made and assembled. Therefore, no appropriate method for making a MEMS device where the core and shell are precisely arranged in close vicinity with each other has been known.
In the field of semiconductor device production, many methods and techniques are known for making micro chips and forming microscopic circuit patterns in multiple-layers. These methods include, for example, lithography, etching, chemical vapor deposition (CVD), electron beam exposure printing or the like. However, these methods can make plane boards or chips, but cannot make a micro spherical body and micro electrodes which are disposed in close vicinity to the micro spherical body.
In U.S. Pat. No. 5,955,776, assigned to the same assignee as the present application and hereby incorporated by reference as if reproduced in its entirety, a method and system for manufacturing spherical-shaped semiconductor integrated circuits is disclosed. A manufacturing process disclosed in the aforementioned patent is used to create and process semiconductor spheres, such as may be used for spherical-shaped semiconductor integrated circuits.